High voltage coaxial connector



W. L. SCHUMACHER HIGH VOLTAGE COAXIAL CONNECTOR Oct. 28, 1969 3Sheets-Sheet 1 Original Filed Oct i Mn H. M P m .NN v R gi A In iINVENTOR. AM Luupow SHDMAGH IR 0a. 28,1969 w. 1.. SCHUMACHER 3. 7

HIGH VOLTAGE COAXIAL CONNECTOR Original Filed Oct. 5, 1964 I 3Sheets-Sheet a I N VEN TOR. WILLIAM LuoLow Scnumcuun United StatesPatent 3,474,532 HIGH VOLTAGE COAXIAL CONNECTOR William LudlowSchurnacher, Camp Hill, Pa., assignor to AMP Incorporated, Harrisburg,Pa.

Original application Oct. 5, 1964, Ser. No. 401,546, now Patent No.3,317,882, dated May 2, 1967. Divided and this application Mar. 7, 1967,Ser. No. 621,197

Int. Cl. H011 43/00; B23p 25/00 US. Cl. 29-628 4 Claims ABSTRACT OF THEDISCLOSURE This application is a division of application Ser. No.401,546, filed Oct. 5, 1964, now Patent No. 3,317,882.

This invention relates to electrical connectors and more particularly toelectrical connectors for use in a high voltage environment.

In high voltage applications, the conductor means carrying the highvoltage has to be terminated at specific locations. These terminationshave to be selected with care in order to preclude the occurrence ofcorona, since, if corona does occur, the efliciency of the high voltageapplication is diminished, and deterioration of the insulating medium atthe terminations occurs.

It is, therefore, an object of the present invention to provide animproved electrical connector suitable for use with high voltages.

Another object of the present invention is to provide an electricalconnector wherein the amount of air therein is reduced to a minimum.

An additional object of the present invention is to provide a highvoltage electrical connector in which corona discharges do not occur.

A still further object of the present invention is to provide a highvoltage electrical connector wherein termination of the center conductoris riveted in place.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there is shown and described an illustrative embodiment of theinvention; it is to be understood, however, that this embodiment is notintended to be exhaustive nor limiting of the invention but is given forpurposes of illustration and principles thereof and the manner ofapplying it in practical use so that they may modify it in variousforms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 is a cross-sectional view of the high voltage electricalconnector connected to a coaxial cable means;

FIGURE 2 is a partial sectional view of FIGURE 1 but on an enlargedscale;

FIGURE 3 is a partial sectional view but on an en larged scale of FIGURE1;

FIGURE 4 illustrates a type of coaxial cable onto which the presentinvention is to be connected;

FIGURES 5-7 illustrate the steps by which the center conductor means ofthe cable means is connected to a center connector element; and

3,474,532 Patented Oct. 28, 1969 FIGURE 8 illustrates a mold to formone-half of the connector.

Turning now to the drawings and more particularly FIGURES 1-4, there isillustrated a high voltage connector C for connection onto a coaxialcable means CM. This coaxial cable means is a high voltage cable and ismanufactured by the Boston Insulated Wire and Cable Company, Boston,Mass., and comprises an outer insulation 1 surrounding a conductivebraid 2 which, in turn, surrounds a semi-conductive tape 3. A dielectricmedium 4 is disposed between tape 3 and another semi-conductive tape 5which, in turn, surrounds another conductive braid 6. A core 7 ofinsulation material is disposed within braid 6 and provides supporttherefor. Coaxial cable means CM is stripped in the manner set forth inFIGURE 1 so that the high voltage connector can be properly connectedthereto.

High voltage connector C comprises two identical members 8 and 9 exceptthat hollow metallic shell 10 includes a flange 12 at its large endwhile the large end of hollow metallic shell 11 includes thread 13.Another minor difference is that center connector element 14 in member 8in which the center conductor is to be secured, has a female section 15in which a male section 16 of similar center connector element 17disposed in member 9 is to be disposed. Since members 8 and 9 areidentical in construction, with the exception of the dififerencespointed out hereinabove, only one member will be described in detail.

Shell 10 is frusto-conical in configuration and has a flat section 18near the small end thereof which extends parallel to the longitudinalaxis. Flat section 18 merges into a tapered section 19 which terminatesat the small end of shell 10. The inner surface of shell 10 isfrusto-conical to a point almost opposite the junction between sections18 and 19 whereupon it merges into a flat surface 21 coaxial with theaxis of shell 10.

Insulating material 22, which is preferably made of silicone rubber, orthe like, is disposed in shell 10, and, as can be perceived, the outersurface of insulating material 22 has a configuration consonant withthat of inner surfaces 20 and 21 of shell 10'. A segment 23 ofinsulating material 22 extends outwardly beyond the small end of shell10 and has a tapered surface 24 in alignment with the tapered surface ofsection 19 so that these tapered surfaces define a frusto-conicalconfiguration. A bore 25 of the same diameter extends centrally throughinsulating material 22 and terminates at an abutting surface 26. Bore 25is in communication with a frusto-conical opening 27 disposed in thelarge diameter end of insulating material 22. Entrance 28' offrusto-conical opening 27 is circular until it merges withfrusto-conical opening 27, as seen in FIGURES 5-7. The surface ofinsulating material 22 between entrance 28 and the edge of the largediameter section of shell 10 is serrated defining spaced circularsections 29, 30 and 31. Sections 29 and 30 extend outwardly beyond theedge of shell 10 while section 31 is in alignment therewith. Part 32 ofinsulating material 22 also extends outwardly from the edge of shell 10.It is to be noted that section 29 extends outwardly further than that ofsection 30, and, of course, section 30 extends outwardly further thansection 31 from the edge of shell 10.

Insulating material 22' of member 9 includes sections 29 and 30' similarto circular sections 29 and 30 of insulating material 22 in member 8 butthat section 31 extends outwardly from the edge of shell 11 further thancorresponding section 31. Thus, the distance measured along circularsections 29 through 31 of insulating material 22 and circular sections29 through 31' of insulating material 22' defines a path which is over10 inches in length.

Center connector element 14 defines a frusto-conical configuration fromfemale section 15 to the end thereof. A bore 33 of constant diameterextends centrally through center connector element 14 and is incommunication with stepped-down sections 34 and 35, which, in turn, arein communication with the interior of female section 15. Entrances 36and 37 of respective sections 35 and 15 are preferably beveled (seeFIGURES 5-7).

Shells and 11, insulating material 22 and 22' and center connectorelements 14 and 17 are assembled to form unitary structures. This isaccomplished by securing center connector elements 14 and 17 and shells10 and 11 to respective mold parts MP (see FIGURE 8) having aconfiguration corresponding to that of circular sections 2931 and 29'-31by means of mandrels M which form bores 25 and 25. Another mold part MPais secured to shells 10 and 11 at their smaller end via the mandrels,and these mold parts MPa form segments 23 and 23'. The inner surface ofshells 10 and 11 and the outer surface of elements 14 and 17 arepreferably coated with a suitable bonding material while the mandrelsare coated with a suitable release agent. Insulating material 22 and 22'is then introduced within shells 10 and 11 through one of the mold partsto form the desired configuration of the insulating material inaccordance with that disclosed. After the insulating material has filledthe void within shells 10 and 11, the insulating material is placedunder vacuum in order to remove all air pockets and render it free ofair as well as to remove all air from the interfaces between the shellsand the insulating material and the center connector elements and theinsulating material. When the insulating material has set, the moldparts and mandrels are removed from shells 10 and 11 which are nowunitary structures.

Of course, it is possible to mold insulating material 22 and 22 in itsdesired form and then insert this material within respective shells 10and 11 with elements 14 and 17 being inserted in their proper places inthe presence of bonding material on the shells and the elements to formthe shell unitary structures.

In assembly, coaxial cable means CM is properly stripped in the mannerillustrated in FIGURES l and 2. If dielectric material 4 is of thewrapped variety, it is preferable to wrap the stripped end thereof witha nylon monofilament or the like in order to preclude any air gapsoccurring therein. Grease is also applied to the forward portion ofdielectric 4 to eliminate any air gap made possible by mismatch ofdielectric 4 and abutting surface 26 of insulating material 22. Theassembly of shell 10, insulating material 22 and center connectorelement 14 is pushed onto the coaxial cable means such that elements 4through 7 pass into bore 25 of insulating ma terial 22 and the taperedsurfaces of sections 23 and 19 of insulating material 22, and shell 10fits underneath semi-conductive tape 3 and braid 2, as shown in FIGURE3, with tape 3 terminating about halfway along the tapered surface ofsection 19. The stripped end of dielectric 4 engages surface 26 andbraid 6 and core 7 extend into bore 33 with the end of braid 6 extendingbeyond entrance 36 while the end of core 7 terminates about midway ofbore 33, as illustrated in FIGURES 2 and 5 through 7. As statedhereinbefore, the grease applied to the stripped end of dielectric 4 isdisposed between surface 26 and the stripped end of dielectric 4 inorder to compensate for any mismatch therebetween, to exclude any airtherefrom, and to form a seal therebetween. This grease is preferably ofthe monoflow type identified as Nebula EP2, which is manufactured by theStandard Oil Company of New Jersey.

As shown in FIGURE 6, the inner sharp edge of center connector element14 extends within semi-conductive tape 5 and dielectric 4 so thatsemi-conductive tape 5 is in engagement With the outer surface of centerconductor element 14.

A Pop rivet assembly 38 of the type manufactured by United ShoeMachinery Corporation, Shelton, Connecticut, comprises a tubular member39 having at one end an outwardly-directed flange 40 and aninwardlydirected flange 41 at the other end. Shank 42 of a pin 43 isdisposed within tubular member 39 and extends outwardly from flange 40.Pin 43 includes a head 44 disposed adjacent flange 41, and area 45between shank 42 and head 44 is of less diameter than that of shank 42.

Pop rivet assembly 38 is inserted within braid 6, stepped sections 34and and into bore 33 of center connector element 14, as illustrated inFIGURE 6. \Vith the Pop rivet assembly in position within centerconnector element 14, a conventional Pop rivet actuating tool (notshown) is placed into engagement with the part of shank 42 extendingoutwardly from flange 40. Upon actuation of the Pop rivet actuatingtool, end 43 moves relative to center connector element 14 causing head44 to move completely within tubular member 39 and coming to a wedgedposition of rest therein within stepped section 35, as illustrated inFIGURE 7.

The action of head 44 moving within tubular member 39 causes flange tobe seated within beveled entrance 36, moves the part of tubular member39 disposed in bore 33 outwardly against braid 6 disposed in bore 33thereby spreading braid 6 against bore 33 and the interface between bore33 and stepped section 34, and, at the same time, shortening the lengthof tubular member 39. The continued movement of head 44 within steppedsection 34 moves the tubular member, in this section, outwardly againstbraid 6 causing the braid to be wedged against stepped section 34effecting excellent electrical and 'meachanical contact. At theinterface between stepped sections 34 and 35, head 44 then comes to restwith parts disposed in stepped sections 34 and 35, and, in doing so,moves the part of tubular section 39 therein outwardly against braid 6causing the braid to be wedged against stepped section 35. After head 44has moved to its position of rest at stepped sections 34 and 35, asillustrated in FIGURE 7, shank 42 is removed from head 44 by additionaltensile force which causes shank 42 to break at area so that shank 42does not remain a part of the Pop rivet assembly after the Pop rivet hasbeen secured in position. The wedging action of tubular member 39against braid 6 becomes progressively increased from bore 33 to steppedsection 35 whereat it reaches its maximum wedging action. The wedgingaction of flange 40 against braid 6 at entrance 36 is also excellent.Thus, as can be discerned, there has been disclosed a unique connectionof the center braid 6 onto center connector element 14 by a rivet meansto provide an excellent electrical and mechanical connection external ofthe critical high voltage field where sharp projections or air of anyamount cannot be tolerated.

Now that braid 6 has been effectively connected to center connectorelement 14, braid 2 and tape 3 are aflixed in intimate contact with thetapered surfaces of sections 19 and 23. A suitable insulating material47, such as, insulating tape is wrapped tightly over braid 2 andsemi-conductive tape 3 so as to exclude any air pockets. Clamp 46 of anydesirable form is used to aflix braid 2 to flat section 18 of metallicshell 10, thus, providing a positive electrical connection as well asproviding mechanical strength. Additional wrapping of insulating tape 47is used to cover the clamp and braid ends. If desired, a conductivepaint or grease may be spread on the surface of cable dielectric medium4 and surface 24 to aid the exclusion of air during this final assemblyoperation. Also, if desirable, insulating material 47 may beaccomplished in any desirable fashion such as, slipping a premolded boothaving a contoured inner surface so as to provide air exclusion frombetween the surfaces of 4 and 24 and tape 3. The same procedure, asoutlined hereinbefore, is followed in connecting the coaxial cable meansto the elements of member 9.

After the coaxial cable means has been connected to the elements ofmembers 8 and 9 of the connector member, members 8 and 9 are ready to bebrought into engagement to interconnect shell 10 with shell 11 andcenter connector element 14 with center connector element 17. Aftermembers 8 and 9 have been brought into engagement, circular sections 29through 31 of insulating material 22 mesh with circular sections 29'through 31' of insulating material 22 and male section 16 of centerconnector element 17 is disposed within female section 15 of centerconnector element 14. Beveled entrance 37 of female section 15 andsemi-circular segmented spring lip 48 on male section 16 facilitate theinsertion of male section 16 within female section 15. The diameter ofsemi-circular spring lip 48 is slightly larger than that of the interiorsurface of female section 15 so that an excellent mechanical andelectrical connection is obtained between center connector element 14and center connector element 17.

In order to draw the edges of members 8 and 9 into a tightly abuttingrelationship, as illustrated in FIGURES 1 and 2, a threaded couplingmember 49 engages flange 12 of shell 10 and threaded section 13 of shell11, and, upon tightening coupling member 49 onto threaded section 13,members 8 and 9 are brought into tight engagement. At this position ofengagement, circular sections 29 through 31 are tightly meshed withcircular sections 29' through 31, which excludes all air therefrom andmale section 16 is properly seated within female section 15. Thus, thepath from engaged shells 10 and 11 to engaged center connector elements14 and 17 is along tightly meshed circular sections 29 through 31 and29' through 31, and is over 10 inches in length, as mentionedhereinbefore. As can be perceived, the points of change in the directionof the path are not in alignment so that these points which are parallelwith the voltage stress between center connector elements 14 and 17 andouter shells 10 and 11 will not have any cumulative effect. The pointsof circular sections 29 and 29 have been arranged to be the furthestfrom the center line of the connector in order to place them at a pointof lower voltage stress in the field because the highest voltage stressoccurs at the surface of inner tape 5 and center connector elements 14and 17.

The electrical connection between male section 16 and female section 15of the center connector elements is made interiorly of the electricalfield so that the space therebetween which contains air does not effectthis connection. Semi-conductive tapes 3 and 5, disposed on each side ofdielectric medium 4, obviate the occurrence of any air between braids 2and 6, since they are in intimate contact With this dielectric medium.Dielectric medium 4 fits snugly within insulating material 22 so that noair is present within the connector. If the surface of dielectric medium4 is not smooth, a grease is used to fill any possible voids.

As can be discerned, there has been disclosed a novel coaxial cableconnector for connection on coaxial cable means carrying high voltageand including a unique connection for the center conductor means.

It will, therefore, be appreciated that the aforementioned and otherdesirable objects have been achieved; however, it should be emphasizedthat the particular embodiment of the invention, which is shown anddescribed herein, is intended as merely illustrative and not asrestrictive of the invention.

What is claimed is:

1. A method of connecting a coaxial connector onto a coaxial cable meanshaving inner and outer conductor means separated by dielectric means,said method comprising the steps of stripping said coaxial cable meansto expose said inner and outer conductor means and dielectric means,placing a metallic shell member having insulation means and centerconnector means therein over said dielectric means and inner conductormeans and under said outer conductor means with said inner conductormeans extending along an opening in said center connector means,securing said outer conductor means to said shell member, and rivetingsaid inner conductor means Within said opening of said center connectormeans.

2. A method according to claim 1 Which includes the further step ofapplying insulation over said outer conductor means, part of said shellmember and onto outer insulation of said coaxial cable means.

3. A method of connecting a hollow conductor member of a coaxial cableto an opening in an electrical connector member comprising the steps ofplacing a section of said hollow conductor member in said opening ofsaid connector member, positioning a conductorsecuring member withinsaid section of said hollow conductor member inside said opening, andforcefully moving an expanding member along an interior surface of saidconductor-securing member thereby expanding at least a portion of saidconductor-securing member against said section of said conductor memberand said opening and thereby wedging said section of said conductormember between said opening and said securing member to provide amechanical and electrical connection between said conductor member andconnector member.

4. A method of connecting a hollow conductor member of a coaxial cableto an opening having stepped areas in an electrical connector membercomprising the steps of placing a section of said conductor memberwithin said opening of said connector member, positioning a hollowconductor-engaging member within said section of said conductor memberwithin said stepped opening, and forcefully moving an expanding memberalong said conductor-engaging member thereby expanding the size of atleast a portion of said conductor-engaging member against said steppedareas and securely wedging said section of said conductor member withinsaid stepped opening therebetween to provide a mechanical and electricalconnection between the conductor member and connector member.

References Cited UNITED STATES PATENTS 2,163,783 6/1939 Fisher 29-4528XR 2,635,501 4/1953 Eichner 72 2,768,105 10/ 1956 Dittmore et al 29-6283,071,399 1/1963 Cronin 29-522 3,120,702 2/1964 Smith 29--527 3,130,4784/ 1964 Stevens 29628 3,332,813 7/1967 Clarke 29527 XR FOREIGN PATENTS904,827 8/ 1962 Great Britain.

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US.Cl. X.R. 29-461, 522, 527

